1. Field of the Invention
The present invention relates to an electronic component device and, more specifically, to an electronic component device in which an electronic component element is mounted on a package substrate that includes an ESD protection element therein. The present invention also relates to a package substrate that includes an ESD protection element therein.
2. Description of the Related Art
For an electronic component device having a precision structure and functioning with high precision, such as an IC device or a SAW device, an important issue is taking measures against electro-static discharge (ESD) and preventing damage to and malfunctioning of the electronic component device if a charged object comes into contact with or is close to the electronic component device.
Traditionally, for example, in an IC device, an IC element itself may include the ESD protection function. However, a problem arises in that it is difficult to further incorporate the ESD protection function into an IC element having high-density functions and also a problem arises in that, even when such incorporation is achieved, it is impossible to provide a sufficiently robust ESD protection function.
In an IC device disclosed in Japanese Unexamined Patent Application Publication No. 10-41458, as illustrated in FIG. 6, an ESD protection component 103 arranged separately from an IC element 102 is mounted on a substrate 101. Specifically, a branch line 104b is branched from a signal line 104a inside the substrate 101, another end of the branch line 104b is extended to the surface of the substrate 101, and that end is connected to the ESD protection component 103.
In this IC device, for example, if an excessive voltage caused by static electricity is applied to a terminal 105, the static electricity is discharged in the ESD protection component 103 and guided to the ground side, and thus, the IC element 102 is not damaged and no malfunction occurs.
However, the method described in Japanese Unexamined Patent Application Publication No. 10-41458 requires that, in addition to the IC element 102, the ESD protection component 103 be mounted on the surface of the substrate 101, and thus, the substrate 101 must have a relatively large surface area. This raises a problem in that the size of the IC device is increased. In addition, a problem arises in that the cost is increased because the ESD protection component 103, which is a separate component, is used.